Deep submergence type buoys



April 20, 1965 s, GROSS 3,178,736

DEEP SUBMERGENCE TYPE BUOYS T4 r: .l.

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ATTORNEY United States Patent 3,178,736 BEEP SUBMERGENCE TYRE BUOYS Seymour Gross, New London, Conn, assignor to the United States of America as represented by the Secretar-y of the Navy Filed Aug. 2, 1963, Ser. No. 299,676 14 Claims. (Cl. 9--8) (Granted under Title 35, US. Code {1952), sec. 266

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to deep submergence type buoys for supporting oceanographic and scientific instruments and apparatus at great depths in the ocean for long periods and where the water pressure may be as high as 15,000 pounds or more per square inch. It is proposed to anchor large numbers of such buoys at large depths and at in tervals in the ocean, each or" which carries scientific instruments such as sonar devices for sending or receiving information, or both, and other instruments. Such buoys must normally meet the following requirements:

(1) It must be structurally capable of resisting water pressures at the depths of submergence, and have little or no water absorbency,

(2) The difference between the weight of the displaced water and the buoys weight in air must be a positive maximum,

(3) Its shape must be such as to provide minimum resistance or drag to the movement of the water,

(4) its useful life of operation must be predictable, especially when using plastic or plastic composite structures which may creep under load,

(5) It must resist strong adhesion thereto by marine creatures,

(6) It must be of low cost per unit of buoyancy and be easily handled on board ship prior to and during the submergence operations.

The use of hollow, closed metal shell buoys such as of aluminum has been proposed for supporting scientific or oceanographic instruments in deep submergcnce in the ocean, but the cost of such buoys capable of deep submergence where the water pressure may be from 10,000 to 15,000 psi. (pounds per square inch) has been so high that large use thereof is economically impractical, and barnacles and other marine creatures may firmly attach themselves to such submerged buoys and reduce their buoyancy.

An object of this invention is to provide a buoy for supporting scientific and other instruments or apparatus submerged in the ocean at great depths of submergence, where the water or sea pressure may be as high as from 10,000 to 15,000 psi. with which the float elements will not shatter, with which loss of buoyancy in a part only of the float elements will not dangerously reduce the total buoyancy of all of the elements, with which marine creatures will not adhere firmly to the float elements, which will have maximum possible buoyancy per unit of volume occupied by the float elements, which will ofler minimum resistance to movement past the buoy of Water in which the buoy is submerged, with which the useful life of the float elements may be predicted with reasonable accuracy, with which creep of the float elements under water pres sure will be a minimum, which may be handled easily and safely on shipboard both prior to and during the submergcnce operations, and which may be relatively inexpensive per unit of buoyancy. 7

Other objects and advantages will appear from the following description of some embodiments of the invention, and the novel features will be particularly pointed out in the appended claims.

3,178,730 ?atentecl Apr. 20, 1965 ice In the accompanying drawings:

FIG. 1 is a schematic illustration of the manner of use of the invention;

FIG. 2 is an elevation, partly in section and on a larger scale than in FIG. 1, of a buoy constructed in accordance with the invention and illustrating the use of spheres as the float elements;

FIG. 3 is an elevation, partly in section, and on a larger scale than in FIG. 2, of a hollow sphere used as one of the float elements;

FIG. 4 is an elevation similar to P16. 2 but illustrating the use of cylindrically shaped float elements;

FIG. 5 is an elevation, partly in section and on a larger scale than in FIG. 4, of hollow cylinders used as float elements;

FiG. 6 is a transverse cross-section of the same, with the section taken approximately along the line 66 of FIG. 5;

FIG. 7 is an elevation, partly in section, of a hexagonally shaped float element that may be used; and

FIG. 8 is a transverse cross-section of the same, with the section taken approximately along the line 8-8 of FIG. 7.

This invention employs a plurality of relatively small float elements of polypropylene, confined in a chamber of a housing that carries scientific or other instruments or apparatus, and which chamber is open to and flooded by the sea in which it may be submerged. The float elements may be of different shapes and sizes and solid or hollow with closed cavities.

In the embodiment of the invention illustrated in FIGS. 13, a housing It carries in its lower part 2 the scientific, oceanographic instruments or apparatus, such as sonar sending and/ or receiving apparatus for example, or devices for measuring and reporting conditions of the ocean where the buoy is to be submerged. The upper part of the housing 1 is a shell 3 that has a plurality of apertures 4 that open from the exterior of the shell into a space or chamber 5 in which a plurality of individual float ele ments 6 are confined. These float elements are formed of polypropylene and in this embodiment are generally spherical in configuration, preferably hollow in which the interior cavity 7 is closed or sealed, as shown in FIG. 3. The spherical shape is advantageous in that such shape has maximum strength against crushing from externally applied water pressure. Each sphere has a spherical cavity which makes the wall approximately uniform in thickness. Barnacles and other marine creatures do not adhere firmly to polypropylene objects and may be brushed off easily.

Polypropylene has a specific gravity of 0.905 and hence is substantially lighter than water, so that even a solid body of polypropylene will not only float in water but has excess buoyancy that aids materially in lifting the apparatus and instruments carried in the housing 1. When the polypropylene body is hollow with a closed cavity therein it is more buoyant than a solid body of the same material, and further adds lifting power to the housing 1 and objects carried thereby. Plastics, including polypropylene, under hydrostatic loading undergo a deformation termed creep or cold flow. Creep or cold flow can be also identified as a continued deformation at room tem perature of the plastic under an applied constant load. Nith plastics at room temperature, it is called cold flow. Recovery is the process of returning to the unstressed state upon the removal of the load. Creep and recovery in compression of polypropylene compression specimens at a constant stress of 2000 psi. for a time cycle of up to 500 hours gave a strain variation of approximately 10,000 to 17,000 micro-inches per inch, and resulted in complete recovery of the propylene in about 24 hours, but for higher stresses the complete recovery occurred after a e3 longer time. The creep and recovery performance of polypropylene bodies Was excellent in comparison with other plastics. Polypropylene can sustain pressures on the order of 14,000 p.s.i. with negligible water absorption. The polypropylene changes dimensions under high pressures and water at greater depths changes volume. At 15,000 p.s.i. of pressure, a theoretical change of volume of fresh water of 3.76 percent, and a theoretical change in volume of solid polypropylene of 2.02 percent, the resultant net theoretical buoyant force per cubic foot of solid polypropylene would be about 7 pounds.

Hollow spheres, with sealed or closed cavities, and having a ratio of wall thickness to mean radius greater than 0.330 did not fail at a pressure of 15,000 psi. The Water absorbed by the hollow spheres while under such pressure was negligible. For deep sea submergence the spheres preferably should not exceed 10 inches in diameter and the minimum acceptable ratio of wall thickness to mean radius for hollow spheres is about 0.290. Hollow spheres of polypropylene that are safe at 15,000 psi. provide a buoyancy at a cost of less than two dollars per pound of buoyancy. The most economic sizes of polypropylene spheres are from 2 to 8 inches in diameter as shown in the following table:

Economic size of polypropylene spheres Where )2 is the wall thickness and R is the mean radius of the wall.

The cost of the buoys now used by the United States Government for deep submergence support of scientific instruments is about $10. to $40. per lb. of buoyance, whereas the cost of buoys in accordance with this invention is as set forth in the table above. The estimated expenditure for 9,000 lbs. buoyancy at $50. per lb. of buoyancy which the Government has paid for metal buoys equals about $450,000 whereas the estimated expenditure for the 9,000 lbs. buoyancy at $1.30 per lb. of buoyancy with polypropylene hollow bodies would be about $11,700. By using a number of small spheres instead of one large sphere, the total cost is less, and if one sphere should fail in use there will be adequate buoyancy left because an excess or necessary buoyancy will be used as a factor of safety.

In the embodiment illustrated in FIGS. 4 and 5, the spheres are replaced by cylindrical floating or buoyant elements 8 with fiat ends 9 arranged in vertical stacks, with the cylinders abutting end to end in each stack. Each element 8 has therein a closed or sealed cavity 10 which has concave hemispherical ends 11 connected by a cylindrical wall, as shown. The crushing pressure is always against a curved wall, whether at the ends or sides, and the curved walls act like arches to resist collapse. The flat abutting ends between cylinders in a stack distributes the lifting pressure between the cylinders over the entire areas of the end faces, whereas with spheres the pressure of one sphere on another is over a much smaller area and hence the pressure per unit area is greater on the spheres than on the ends of cylinders.

In the embodiment illustrated in FIGS. 7 and 8 the floating elements 12 are similar to the elements 3 of FIGS. and 6 except that the exterior side wall of each element is hexagonal instead of cylindrical as in FIGS. 5 and 6, so that the hexagonal shapes will nest with one another better than when the elements are cylindrical or spherical. Hence more polypropylene bodies of hexagonal shape may be arranged in a given volume in the confining shell 3 than with other shapes, thus increasing the lifting power of the floating elements available in a given volume in shell 3. Each element 12 has a concave semipherical end 13 for its closed cavity 14, and these ends 13 are connected by a cylindrical side wall as in FIGS. 5 and 6.

In use the housing 1 is held submerged, as by connect ing it by a cable 15 to a weight 16, so that the floating elements 6, 8 or 12 will be held at a great depth in the sea where the pressure may be as high as 15,000 p.s.i. or more.

The voids between the small polypropylene bodies or elements in the shell or cage 3 may be filled with very small solid or hollow bodies of polypropylene which is lighter than water, to give added lifting buoyance to the shell or cage 3.

It will be understood that various changes in the details, proportions, materials, shapes and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art Within the principle and scope or" the invention, as expressed in the appended claims.

I claim:

1. A subsurface device for supporting oceanographic and scientific instruments while submerged at large depths in the ocean, which comprises:

(a) a housing with one chamber for carrying such instruments and having another and separate chamber open to and flooded by the sea, and

(b) a plurality of separate float elements confined in said another chamber and formed of polypropylene.

2. The device according to claim 1, wherein said elements are spherical in shape.

3. The device according to claim 1, wherein said elements are closed, hollow spheres.

4. The device according to claim 1, wherein said elements are hollow and have closed interior spaces which have concave, semispherical end walls and cylindrical walls connecting said end walls.

5. The device according to claim 1, wherein said elements have exterior opposite fiat ends connected by sides that are hexagonal in cross-section, and are disposed in said separate chamber in vertical positions with the flat ends abutting one another, and nested side by side, with their hexagonal horizontal cross-sections abutting one another.

6. A deep submergence type buoy for supporting scientific instruments at great depths in the ocean, which comprises:

(a) a housing for carrying said instruments and having therein a chamber open to and floated by the sea, and

(b) a plurality of separate float elements of polypropylene confined in said chamber and abutting one another.

7. The buoy according to claim 6, wherein said float elements are approximately spherical in shape and have diameters of less than 10 inches.

8. The buoy according to claim 6, wherein said heat elements are hollow with closed interior cavities.

9. The buoy according to claim 6, wherein said float elements are hollow spheres with closed interior cavities.

10. The buoy according to claim 6, wherein said float elements are hollow closed spheres with closed interiors and have a ratio of wall thickness to mean radius greater than about 0.290 and the outside diameters of the spheres are less than about ten inches.

11. The buoy according to claim 6, wherein the float elements are approximately hollow spheres with closed interior cavities, with a ratio of wall thickness to mean radius greater than about 0.290.

12. The buoy according to claim 6, wherein the fioat elements are generally cylindrical in shape, arranged 5 upright in said chamber with ends of the elements abutting in vertically stacked groups.

13. The buoy according to claim 6, wherein the float elements are generally cylindrical in shape arranged vertically with ends abutting in vertical stacks, and each element having a closed interior cavity with a cylindrical side wall and semispherical ends.

14. The device according to claim 1, wherein each of said elements has a closed, hollow, interior, spherical chamber.

References Cited by the Examiner UNITED STATES PATENTS 10 FERGUS S. MIDDLETON, Primary Examiner. 

1. A SUBSURFACE DEVICE FOR SUPPORTING OCEANOGRAPHIC AND SCIENTIFIC INSTRUMENTS WHILE SUBMERGED AT LARGE DEPTHS IN THE OCEAN, WHICH COMPRISES: (A) A HOUSING WITH ONE CHAMBER FOR CARRYING SUCH INSTRUMENTS AND HAVING ANOTHER AND SEPARATE CHAMBER OPEN TO THE FLOODED BY THE SEA, AND (B) A PLURALITY OF SEPARATE FLOAT ELEMENTS CONFINED IN SAID ANOTHER CHAMBER AND FORMED OF POLYPROPYLENE. 